Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.4.3.11 (glutamate dehydrogenase)
 4,437 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. In epididymal adipose tissue synthesizing fatty acids from fructose in vitro, addition of insulin led to a moderate increase in fructose uptake, to a considerable increase in the flow of fructose carbon atoms to fatty acid, to a decrease in the steady-state concentration of lactate and pyruvate in the medium, and to net uptake of lactate and pyruvate from the medium. It is concluded that insulin accelerates a step in the span pyruvate-->fatty acid. 2. Mitochondria prepared from fat-cells exposed to insulin put out more citrate than non-insulin-treated controls under conditions where the oxaloacetate moiety of citrate was formed from pyruvate by pyruvate carboxylase and under conditions where it was formed from malate. This suggested that insulin treatment of fat-cells led to persistent activation of pyruvate dehydrogenase. 3. Insulin treatment of epididymal fat-pads in vitro increased the activity of pyruvate dehydrogenase measured in extracts of the tissue even in the absence of added substrate; the activities of pyruvate carboxylase, citrate synthase, glutamate dehydrogenase, acetyl-CoA carboxylase, NADP-malate dehydrogenase and NAD-malate dehydrogenase were not changed by insulin. 4. The effect of insulin on pyruvate dehydrogenase activity was inhibited by adrenaline, adrenocorticotrophic hormone and dibutyryl cyclic AMP (6-N,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate). The effect of insulin was not reproduced by prostaglandin E(1), which like insulin may lower the tissue concentration of cyclic AMP (adenosine 3':5'-cyclic monophosphate) and inhibit lipolysis. 5. Adipose tissue pyruvate dehydrogenase in extracts of mitochondria is almost totally inactivated by incubation with ATP and can then be reactivated by incubation with 10mm-Mg(2+). In this respect its properties are similar to that of pyruvate dehydrogenase from heart and kidney where evidence has been given that inactivation and activation are catalysed by an ATP-dependent kinase and a Mg(2+)-dependent phosphatase. Evidence is given that insulin may act by increasing the proportion of active (dephosphorylated) pyruvate dehydrogenase. 6. Cyclic AMP could not be shown to influence the activity of pyruvate dehydrogenase in mitochondria under various conditions of incubation. 7. These results are discussed in relation to the control of fatty acid synthesis in adipose tissue and the role of cyclic AMP in mediating the effects of insulin on pyruvate dehydrogenase.
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PMID:Regulation of adipose tissue pyruvate dehydrogenase by insulin and other hormones. 515 98

Effects of norepinephrine on gluconeogenesis and ureogenesis from glutamine by hepatocytes from fasted rats were assessed. Comparisons were made to asparagine metabolism and to the effects of NH4Cl and dibutyryl cyclic AMP. With asparagine as substrate, aspartate content was very high but norepinephrine, dibutyryl cyclic AMP, or NH4Cl had little effect on gluconeogenesis or ureogenesis. Metabolism of asparagine could be greatly enhanced by the combination of oleate, ornithine, and NH4Cl. However, even under these conditions, asparatate content remained high, and norepinephrine and dibutyryl cyclic AMP had little influence on glucose or urea synthesis. With glutamine as substrate, aspartate content was much lower, but was greatly elevated by norepinephrine, dibutyryl cyclic AMP, or NH4Cl. Each of these effectors strongly stimulated glucose and urea formation from glutamine. NH4Cl stimulation was accompanied by an increased glutamate and decreased alpha-ketoglutarate content. This suggests the mechanism for NH4Cl stimulation is a near-equilibrium adjustment to ammonia by glutamate dehydrogenase and aspartate aminotransferase rather than a principal involvement of glutaminase. Although both norepinephrine and dibutyryl cyclic AMP lowered alpha-ketoglutarate to the same extent, norepinephrine more rapidly increased aspartate content and led to a smaller accumulation of glutamate than did dibutyryl cyclic AMP. Moreover, only norepinephrine led to a rapid increase in succinyl-CoA concentration. The catecholamine effect could not be explained by specific changes in cytosolic or mitochondrial redox states. The results suggest that alpha-ketoglutarate dehydrogenase is a site of catecholamine action in rat liver. Since purified alpha-ketoglutarate dehydrogenase is known to be Ca2+ stimulated and Ca2+ flux is involved in catecholamine action, these findings also suggest that mitochondrial Ca2+ is elevated by catecholamines.
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PMID:Glutamine metabolism of isolated rat hepatocytes. Evidence for catecholamine activation of alpha-ketoglutarate dehydrogenase. 609 58

1. The specific activity of NADP-dependent L-glutamate dehydrogenase (GDH) from T. cruzi epimastigotes increased from 0.7 at early log-phase to 1.4 mumol/min/mg of protein at the stationary phase. 2. When T. cruzi cells were incubated in the presence of L-glutamate (0.08%), the GDH had a specific activity of 2.2, much higher than that of cells incubated in the presence of D-glucose (0.08%), which was 1.2 mumol/min/mg of protein. 3. The specific activity of NADP-dependent GDH from cells incubated in the presence of L-glutamate did not vary when the cells were treated with cycloheximide (100 ng/ml) or chloramphenicol (0.5 mg/ml). 4. The activity of the NAD-dependent GDH did not change in any of the situations described above. 5. AMP, ADP, ATP, citrate, isocitrate, oxaloacetate, fructose-1,6-diP, pyruvate, L-proline and L-arginine did not have any effect on the NADP-linked GDH activity. Product inhibition studies were done on the latter GDH activity.
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PMID:Regulatory studies of L-glutamate dehydrogenase from Trypanosoma cruzi epimastigotes. 613 80

The effect of 3-mercaptopicolinate, an inhibitor of phosphoenolpyruvate carboxykinase [GTP:oxaloacetate carboxy-lyase (transphosphorylating), EC 4.1.1.32], was tested on NH3 formation via the purine nucleotide cycle and glutamate dehydrogenase (EC 1.4.1.2). NH3 excretion in rats increased 70-fold after 48 h of NH4Cl feeding, from 12.2 +/- 4.5 to 862 +/- 190 mumol/mg of creatinine. At 4 h after a single intraperitoneal injection of 3-mercaptopicolinate into NH4Cl-fed rats, NH3 excretion was inhibited by 93%. Kidneys of NH4Cl-fed plus 3-mercaptopicolinate-treated rats, compared with those of NH4Cl-fed rats, showed a 3.5-fold increase in the content of IMP, 5-fold increase in adenylosuccinate, 4-fold increase in aspartate, and a 30% increase in AMP. 3-Mercaptopicolinate completely inhibited NH3 and glucose formation from glutamate in tubules from acidotic rats and NH3 formation from aspartate in kidney perfusion experiments. When transamination in tubules was prevented by 2-amino-4-methoxy-trans-but-3-enoic acid, formation of glucose, but not of NH3, from glutamate was inhibited. 3-Mercaptopicolinate completely inhibited NH3 formation from aspartate in the presence of the aminotransferase inhibitor in kidney tubules. The data show that NH3 can be formed via glutamate dehydrogenase and the purine nucleotide cycle at significant and approximately equal rates. 3-Mercaptopicolinate has no direct effect on NH3 formation via glutamate dehydrogenase, but inhibits that via the purine nucleotide cycle. We conclude that gluconeogenesis is not regulatory for NH3 formation in kidney.
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PMID:The relationship between glutamate deamination and gluconeogenesis in kidney. 613 15

Fourteen stable mutants of Mucor bacilliformis which grew yeastlike under both aerobic and anaerobic conditions were isolated after treatment of growing mycelium with N-methyl-N'-nitro-N-nitrosoguanidine. Biochemical characterization of the mutants included determination of growth in different carbon and nitrogen sources, determination of sensitivity of respiration to cyanide and salicylhydroxamate, analysis of cytochrome spectra, determination of glutamate dehydrogenases, glutamine synthase, and ornithine decarboxylase activities, and measurement of cyclic AMP levels. Data showed that all mutants were defective in some aspect of oxidative metabolism and had low levels of ornithine decarboxylase, whereas other characters were variable. It was concluded that morphological transition in M. bacilliformis is probably associated with mitochondrial functions and expression of ornithine decarboxylase, but may be independent of cyclic AMP and glutamate dehydrogenase levels. The importance of genetic studies in the analysis of dimorphism is stressed.
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PMID:Isolation and biochemical analysis of Mucor bacilliformis monomorphic mutants. 613 77

A method for measuring free fatty acids by enzymic cycling is described. Free fatty acids are converted to acyl-CoAs by acyl-CoA synthetase, then the acyl-CoAs are hydrolyzed back to the free fatty acids by acyl-CoA hydrolase in a cyclic fashion. The amounts of AMP produced during this cyclic reaction are determined from the absorbance at 340 nm in the presence of AMP deaminase and glutamate dehydrogenase. This method is sensitive to as low as 0.1 nmol of free fatty acids, and the standard curve is linear up to 1.0 nmol. This method shows a broad specificity for long-chain fatty acids (C12--C20) and the recoveries of fatty acids added to bacterial cell-free extracts are more than 90%.
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PMID:An enzymic cycling method for the determination of free fatty acids with acyl-CoA synthetase and acyl-CoA hydrolase. 613 47

Glutamic dehydrogenase extracted with tris buffer from fresh freeze-thawed rat heart mitochondria was purified by ammonium sulphate fractionation, affinity chromatography on GTP agarose, hydroxyapatite chromatography and concentration using a molecular sieve. The final specific activity is 80 units/mg protein. Thin gel SDS electrophoresis of the purified enzyme preparation after reduction with dithiothreitol shows a major band with a molecular weight of 38 000 Daltons. Two minor bands are also present. Sucrose density gradient centrifugation reveals a molecular weight of 230 000 Daltons for unreduced mitochondrial GDH activity. By gel filtration rat heart mitochondrial glutamic dehydrogenase has a major peak at 230 000 Daltons, a minor peak at 300 000 Daltons and some larger molecular weight species. Rat liver mitochondrial glutamic dehydrogenase has a minor peak at 230 000, a major peak at 300 000 and some larger molecular weight species. The rat liver mitochondrial glutamic dehydrogenase predominance at 300 000 is unchanged by incubation, extraction and purification with rat heart mitochondria. The purified GDH is stable frozen at -10 degrees C in tris-HCl buffer with EDTA. It loses activity at 4 degrees C especially when stored in 0.2 M phosphate buffer. It also loses activity when dialyzed for 24 h. This loss of activity is not completely prevented by adding nucleotides to the buffer (AMP or ADP) but is decreased by their presence.
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PMID:Glutamic dehydrogenase from rat heart mitochondria. I. Purification and physical properties including molecular weight determination. 672 19

The effect of chronic acid feeding and its subsequent withdrawal was determined on the amounts of the metabolic intermediates and enzymic activities of the purine nucleotide cycle. Sprague-Dawley rats were given 1.5% (w/v) NH4Cl in their drinking water for 5 days. The renal excretion of NH3 rose 70-fold and the rats developed acidosis. The amount of renal IMP rose from a control value of 4.5 +/- 2.2 to 20.4 +/- 3.7nmol/g of kidney after 48h of acid feeding (P less than 0.001) and fell to normal within 48h of the recovery. Adenylosuccinate concentrations fell from a control value of 4.5 +/- 0.9nmol/g of kidney to 1.2 +/- 0.3nmol/g (P less than 0.005) by day 5 of acidosis and continued to fall to undetectable values by 48h after recovery. The amount of AMP remained constant through the acid-feeding and the recovery periods. The activity of adenylosuccinate synthetase, the rate-limiting enzyme of the purine nucleotide cycle, paralleled the rise and fall in NH3 excretion. The activities of phosphate-dependent glutaminase and glutamate dehydrogenase were elevated during the acid-feeding and the recovery period. Thus changes in the purine nucleotide cycle correlate with changes in NH3 excretion to a more parallel degree than does the activity of glutaminase or glutamate dehydrogenase.
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PMID:The purine nucleotide cycle in the regulation of ammoniagenesis during induction and cessation of chronic acidosis in the rat kidney. 730 74

The effect of different adenine-containing compounds on the NADP-/NAD-glutamate dehydrogenase (GDH) ratio was studied as a function of yeast-mycelium transition in Benjaminiella poitrasii. Under in vivo conditions, at a 5.0 mM concentration, cyclic AMP (cAMP) and dibutyryl cAMP maintained the cells in the yeast form for up to 7 and 5 h, respectively, and this was reflected in the patterns of GDH ratios observed. In vitro studies of phosphorylation and dephosphorylation have also been carried out, and the results suggest a possible correlation between cAMP, the GDH ratio, and cell form in B. poitrasii.
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PMID:Possible involvement of cyclic adenosine 3',5'-monophosphate in the regulation of NADP-/NAD-glutamate dehydrogenase ratio and in yeast-mycelium transition of Benjaminiella poitrasii. 839 89

Photoaffinity labeling with [alpha-32P]8N3GTP and [gamma-32P]8N3GTP was used to identify the guanine binding domain of the GTP regulatory site within glutamate dehydrogenase (GDH). Without photolysis, 8N3GTP mimicked the regulatory properties of GTP on GDH activity with 8N3GTP exhibiting a Ki of 5 microM while the Ki for GTP was about 0.6 microM. Under optimal photolabeling conditions saturation of photoinsertion with 1 microgram of GDH revealed an apparent Kd of 9 +/- 4 microM for [gamma-32P]8N3GTP. Photolabeling with this analog could be competitively inhibited with GTP with an apparent Kd of 12 +/- 2 microM. Other nucleotides such as ATP and NAD(P)H could not reduce the amount of photoinsertion as effectively as GTP. ADP could decrease photoinsertion, but only at much higher concentrations. NAD(P)+, GDP, AMP, and GMP had little effect on photoinsertion. Divalent cations Mg2+ and Ca2+ also reduced photoinsertion significantly while the monovalent K+ and Na+ ions had no effect. Aluminum(III)-chelate or iron(III)-chelate affinity chromatography and reversed-phase HPLC were used to purify photolabel-containing peptides generated with either trypsin or chymotrypsin. This identified a portion of the guanine binding domain within the GTP regulatory site as the region containing the sequence Ile439 to Tyr454. Photolabeling of this peptide was prevented 91% by the presence of 300 microM GTP during photolysis. Lys445 was not identified in sequence analyses of the photolabeled peptides. Also, trypsin was unable to cleave the photolabeled peptide at this site. These results suggest that Lys445 may be the residue modified by [alpha-32P]8N3GTP.
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PMID:Identification of a guanine binding domain peptide of the GTP binding site of glutamate dehydrogenase: isolation with metal-chelate affinity chromatography. 843 45


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